2.8 Where have the 'other' tabs gone?
They don't exist in that way now, the bulk of the info concerning tools are in the topbar. Add-ons are not yet ready for reintroduction in 2.8, and when they are done with the API then we will get an idea of how they will be accessed. Quite possible we will get special pop up panels if we want since they are now solving the window parenting issues.